I love my Smart wool top. I have been doing training and races for close to 25 years and I have tried all kinds of warm weather gear. This is truly the best. I wore it for a 14 mile trail run the other day in 27 degree weather and it kept me so toasty. It wicked the sweat away from my skin and I never got chilled. I did have a thin shortsleeve layer under it but I was amazed how well it preformed. It is ver pricey at 100+ dollars but you get what you pay for. Make sure to store it in a container that prevents moths during the off months. My favorite Smart Wool hat was eaten last year stored in my dresser.